Grok 4 Fast Non-Reasoning overview
Grok 4 Fast Non-Reasoning by xAI
Its design prioritizes speed and stability for efficient handling of large-scale textual data.
Grok 4 Fast Non-Reasoning specs
- Model ID
x-ai/grok-4-fast-non-reasoning- Developer
- xAI
- Context window
- 2,000,000 tokens
- Max output
- 1,999,000 tokens
- Input
- Text
- Output
- Text
- API
- OpenAI-compatible, base URL
https://api.aimlapi.com/v1
Grok 4 Fast Non-Reasoning is a specialized variant of xAI's Grok 4 model optimized for ultra-high context capacity and rapid text-to-text tasks without advanced reasoning capabilities. It focuses on handling extremely long contexts up to 2,000,000 tokens efficiently, delivering fast, deterministic outputs suitable for high-throughput applications.
Performance Benchmarks
- Context Window: 2,000,000 tokens
- Max Output: Variable, optimized for streaming and fast response
- Training Regime: Streamlined for speed and large-context encoding, non-reasoning focused
- Tool Use: Not supported (non-agentic)
Performance Metrics
Grok 4 Fast Non-Reasoning is specifically optimized to handle extremely large context windows up to 2 million tokens, enabling it to process vast amounts of text without losing coherence. While it does not support advanced multi-step reasoning or tool integration, it delivers highly efficient and stable performance in text-to-text generation tasks where context retention over long sequences is critical. Its architecture prioritizes speed and throughput, allowing for rapid response times even with very large inputs. This makes it ideal for applications such as long document summarization, extensive conversational histories, and batch processing where reasoning complexity is not required. The model’s deterministic output further ensures consistent and reliable behavior across repeated requests.
Key Capabilities
- Handles ultra-long context windows (up to 2 million tokens) for large document and multi-document processing
- Rapid text-to-text generation optimized for latency-sensitive applications
- Deterministic and non-streaming responses for stable output consistency
- Scalable for API-driven environments with efficient cached pricing support
Optimal Use Cases
- Large-scale document summarization and analysis
- Context-rich text completion across lengthy inputs
- Fast-response conversational AI handling extensive histories
- Batch text generation in content or data pipelines requiring consistent context retention
Comparison with Other Models
vs. Grok 4: Grok 4 Fast Non-Reasoning trades advanced multi-step reasoning and tool integration for vastly expanded context capacity and faster throughput, making it suitable for applications where reasoning is not critical but context scale is.
vs. GPT-4o: Grok 4 Fast Non-Reasoning surpasses GPT-4o in maximum context length by nearly an order of magnitude, though it lacks multimodal and reasoning features available in GPT-4o.
vs. Grok 4 Fast Reasoning: Grok 4 Fast Non-Reasoning offers higher speed and larger context but omits complex reasoning capabilities present in reasoning-enabled variants.
Limitations
- Lacks multi-step reasoning and agentic tool use
- Text-only modality, no vision/audio processing
- Closed-weight model without local offline inference
- Streaming determinism may vary depending on context size
Use cases
- Large-scale document summarization and analysis
- Context-rich text completion across lengthy inputs
- Fast-response conversational AI handling extensive histories
- Batch text generation in content or data pipelines requiring consistent context retention
Capabilities
- Function calling
- Streaming
Grok 4 Fast Non-Reasoning benchmarks by 
Artificial Analysis
See how Grok 4 Fast Non-Reasoning scores on independent evaluations. Data retrieved Nov 3, 2026.
Benchmark results
Compare 10 models available on AI/ML API across 5 independent benchmarks.
Humanity's Last Exam
Expert-written questions across academic subjects.
GPQA Diamond
Graduate-level science questions written to resist web search.
AA-LCR
Reasoning across long documents of about 100k tokens.
IFBench
Following precise instructions about the shape of the answer.
τ²-Bench Telecom
Customer support agent tasks with tool calls.
Grok 4 Fast Non-Reasoning API pricing
| Usage | Price | Unit |
|---|---|---|
| Input | $1.25 | 1M tokens |
| Output | $2.5 | 1M tokens |
| Cached input | $0.2 | 1M tokens |
Prices from the AI/ML API price list, checked on Nov 4, 2026.
Grok 4 Fast Non-Reasoning vs other models: token prices
AI/ML API input and output rates for 5 models, per million tokens.
| Model | Input | Output |
|---|---|---|
 Grok 4 Fast Non-Reasoning | $1.25 | $2.5 |
| Grok Build 0.1 | $1 | $2 |
| Grok 4.7 | $2 | $6 |
| Grok 4.6 | $2 | $6 |
| Grok 4.5 | $2 | $6 |
How to use the Grok 4 Fast Non-Reasoning API
View docs
Build with your agent
Give your agent the model details, code and documentation.
1Get your API key
Create API keyexport AIMLAPI_KEY="8f2b4c7d9a1e6b3f…"2Make your first request
curl 'https://api.aimlapi.com/v1/chat/completions' \
-H "Authorization: Bearer $AIMLAPI_KEY" \
-H 'Content-Type: application/json' \
-d '{
"model": "x-ai/grok-4-fast-non-reasoning",
"messages": [
{
"role": "user",
"content": "Write a haiku about the ocean."
}
]
}'import os
import requests
headers = {
"Authorization": f"Bearer {os.environ['AIMLAPI_KEY']}",
"Content-Type": "application/json",
}
payload = {
"model": "x-ai/grok-4-fast-non-reasoning",
"messages": [
{
"role": "user",
"content": "Write a haiku about the ocean."
}
]
}
response = requests.post("https://api.aimlapi.com/v1/chat/completions", headers=headers, json=payload, timeout=120)
response.raise_for_status()
print(response.json())const response = await fetch("https://api.aimlapi.com/v1/chat/completions", {
method: "POST",
headers: {
Authorization: `Bearer ${process.env.AIMLAPI_KEY}`,
"Content-Type": "application/json",
},
body: JSON.stringify({
"model": "x-ai/grok-4-fast-non-reasoning",
"messages": [
{
"role": "user",
"content": "Write a haiku about the ocean."
}
]
}),
});
if (!response.ok) throw new Error(`HTTP ${response.status}`);
console.log(await response.json());Models similar to Grok 4 Fast Non-Reasoning
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Grok 4 Fast Non-Reasoning FAQ
What is the context window of Grok 4 Fast Non-Reasoning?
Grok 4 Fast Non-Reasoning has a 2,000,000 tokens context window and can return up to 1,999,000 tokens.
What inputs and outputs does Grok 4 Fast Non-Reasoning support?
Grok 4 Fast Non-Reasoning takes image, text as input and returns text.
What is the model ID for Grok 4 Fast Non-Reasoning?
Use x-ai/grok-4-fast-non-reasoning as the model id. Requests go to https://api.aimlapi.com/v1/chat/completions.
How much does Grok 4 Fast Non-Reasoning cost?
Grok 4 Fast Non-Reasoning costs $1.25 input and $2.5 output per 1M tokens on AI/ML API, billed as you go with no subscription.
Does Grok 4 Fast Non-Reasoning support streaming?
Yes, Grok 4 Fast Non-Reasoning can stream responses as they are generated.
Can Grok 4 Fast Non-Reasoning read images?
Yes, Grok 4 Fast Non-Reasoning accepts image input alongside text.
Who created Grok 4 Fast Non-Reasoning?
Grok 4 Fast Non-Reasoning was built by xAI .
What is Grok 4 Fast Non-Reasoning designed for?
It is built to give faster responses with lower latency by skipping the reasoning step.
Can Grok 4 Fast Non-Reasoning use tools or function calls?
Yes, it supports function calling, parallel tool calls, and tool use, though it does not perform extended reasoning.